Power management integrated circuit

ABSTRACT

A central processing unit (CPU) is disclosed. The CPU includes a CPU die; and a power management die bonded to the CPU die in a three dimensional packaging layout.

COPYRIGHT NOTICE

Contained herein is material that is subject to copyright protection.The copyright owner has no objection to the facsimile reproduction ofthe patent disclosure by any person as it appears in the Patent andTrademark Office patent files or records, but otherwise reserves allrights to the copyright whatsoever.

FIELD OF THE INVENTION

The present invention relates to computer systems; more particularly,the present invention relates to delivering power to a centralprocessing unit (CPU).

BACKGROUND

The magnitude of power generated at CPUs is becoming an increasingconcern as processing speeds increase. Thus, current power managementschemes take advantage of reduced CPU activity to manage the magnitudeof power consumed. However, power management circuitry is typicallylocated at a remote location, such as on the CPU motherboard. ManagingCPU power from the motherboard typically does not provide for asufficiently fast response.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated by way of example and not limitation in thefigures of the accompanying drawings, in which like references indicatesimilar elements, and in which:

FIG. 1 is a block diagram of one embodiment of a computer system;

FIG. 2 illustrates one embodiment of a CPU die;

FIG. 3 illustrates one embodiment of a power management die; and

FIG. 4 illustrates one embodiment of a CPU.

DETAILED DESCRIPTION

According to one embodiment, a power management system for a CPU isdescribed. In the following detailed description of the presentinvention, numerous specific details are set forth in order to provide athorough understanding of the present invention. However, it will beapparent to one skilled in the art that the present invention may bepracticed without these specific details. In other instances, well-knownstructures and devices are shown in block diagram form, rather than indetail, in order to avoid obscuring the present invention.

Reference in the specification to “one embodiment” or “an embodiment”means that a particular feature, structure, or characteristic describedin connection with the embodiment is included in at least one embodimentof the invention. The appearances of the phrase “in one embodiment” invarious places in the specification are not necessarily all referring tothe same embodiment.

FIG. 1 is a block diagram of one embodiment of a computer system 100.Computer system 100 includes a central processing unit (CPU) 102 coupledto bus 105. In one embodiment, CPU 102 is a processor in the Pentium®family of processors including the Pentium® II processor family,Pentium® III processors, and Pentium® IV processors available from IntelCorporation of Santa Clara, Calif. Alternatively, other CPUs may beused.

A chipset 107 is also coupled to bus 105. Chipset 107 includes a memorycontrol hub (MCH) 110. MCH 110 may include a memory controller 112 thatis coupled to a main system memory 115. Main system memory 115 storesdata and sequences of instructions that are executed by CPU 102 or anyother device included in system 100. In one embodiment, main systemmemory 115 includes dynamic random access memory (DRAM); however, mainsystem memory 115 may be implemented using other memory types.Additional devices may also be coupled to bus 105, such as multiple CPUsand/or multiple system memories.

Chipset 107 also includes an input/output control hub (ICH) 140 coupledto MCH 110 to via a hub interface. ICH 140 provides an interface toinput/output (I/O) devices within computer system 100. For instance, ICH140 may be coupled to a Peripheral Component Interconnect bus adheringto a Specification Revision 2.1 bus developed by the PCI SpecialInterest Group of Portland, Oreg.

FIG. 2 illustrates one embodiment of a CPU 102 die 200. Die 200 includesfour CPU processing cores (core 1-core 4) 210. In addition, die 200includes cache 220 and I/O circuitry 230. In one embodiment, cache 220is a L2/L3 cache. I/O circuitry 230 is placed on the periphery (e.g.,north, south, east, and west boundaries) to enable efficient verticalcurrent delivery to cores 210

As discussed above, circuitry situated on the motherboard does notprovide a sufficient response for power management of a CPU die. Inparticular, the temperature and activity factor of CPUs change over timeduring operation due to varying workloads of applications. In addition,on-die Vcc values change due to noises induced by current transients.

Typically CPU frequency is set based on worst-case Vcc and temperature.As the activity factor and temperature change, energy efficiency of theCPU degrades since the optimal Vcc/Vt ratio at constant frequency is afunction of activity and temperature. Off-chip VRMs and body biasgenerators have very large response times and thus their usefulness fordynamic control is limited.

According to one embodiment, a power management die is bonded to CPU die200. FIG. 3 illustrates one embodiment of a power management die 300.Die 300 includes VRM 310, body bias generators 320, temperature sensor330, voltage sensor 335 and control circuits 340.

In one embodiment, VRM die 310 provides a regulated voltage supply tocomponents within CPU die 200. For instance VRM 310 supplies Vccvoltages to Core 1-Core 4, cache 220 and I/O components 230. Body biasgenerators 320 adjust the body bias voltages of transistors on die 200.Particularly, a non-zero body to source bias is generated to modulatethe threshold voltage of the die 200 transistors to control leakage andfrequency.

Temperature sensor 330 measures the temperature of die 200, whilevoltage sensor 335 measures the operating voltage. Control circuits 340controls the transistors on die 200. In addition, control circuits 340dynamically determine the optimum body voltage for the die 200transistors. In a further embodiment, die 300 may include a clock sensor360, a current sensor 370 and a power sensor 380.

According to one embodiment, if the workload is known ahead of time, theVcc, Vbs and frequency of die 200 can be set to the optimal value tomaximize energy efficiency for the workload. Moreover, the time tochange Vcc and Vbs should be made is small since having components suchas VRM 310 and body bias generators 320 bonded to die 200 provides afast response time.

According to one embodiment, die 300 is flipped and bonded (metal-sideto metal-side), thus bringing the various power management components asclose to the CPU die 200 as possible. In a further embodiment, VRM die300 is in a three dimensional (3D) packaging configuration with die 200.

FIG. 4 illustrates one embodiment of CPU 102. CPU 102 includes themulti-Vcc VRM die 300 sandwiched between CPU die 200 and a packagesubstrate 400. According to one embodiment, VRM die 300 is pad matchedto CPU die 200 and package substrate 400 so that die 300 can be anoption sandwiched die. Thus, package 400 and CPU 200 design does notneed any changes. In addition, FIG. 4 shows the I/O connections betweendie 200 and 300, as well as the die/die bonding. A heat spreader andheat sink (not shown) may be coupled to CPU die 200.

Whereas many alterations and modifications of the present invention willno doubt become apparent to a person of ordinary skill in the art afterhaving read the foregoing description, it is to be understood that anyparticular embodiment shown and described by way of illustration is inno way intended to be considered limiting. Therefore, references todetails of various embodiments are not intended to limit the scope ofthe claims, which in themselves recite only those features regarded asessential to the invention.

1. A central processing unit (CPU) comprising: a CPU die; and a powermanagement die bonded to the CPU die in a three dimensional assembly. 2.The CPU of claim 1 wherein the power management die comprises: a voltageregulator module (VRM) to supply a voltage to components at the CPU die;and a body bias generator to adjust body voltages of transistor deviceson the CPU die.
 3. The CPU of claim 2 wherein the power management diefurther comprises: a temperature sensor; and a voltage sensor.
 4. TheCPU of claim 3 wherein the power management die further comprises acontrol circuit to control the transistors on the CPU die.
 5. The CPU ofclaim 4 further comprising I/O connections coupled between the powermanagement die and the CPU die.
 6. The CPU of claim 1 further comprisinga package substrate bonded to the power management die.
 7. The CPU ofclaim 6 wherein the power management die is pad matched to the CPU dieand the package substrate.
 8. The CPU of claim 1 wherein the powermanagement die is flipped and bonded to the CPU die metal side to metalside.
 9. A method comprising bonding a power management die to a centralprocessing unit (CPU) die in a three-dimensional assembly.
 10. Themethod of claim 9 further comprising bonding a package substrate to thepower management die.
 11. The method of claim 10 wherein the powermanagement die is pad matched to the CPU die and the package substrate.12. The method of claim 9 further comprising coupling I/O connectionsbetween the power management die and the CPU die.
 13. A systemcomprising: a central processing unit (CPU) having: a CPU die; and apower management die bonded to the CPU die in a three dimensionalassembly; a chipset coupled to the CPU; and a main memory device coupledto the chipset.
 14. The system of claim 13 wherein the power managementdie comprises: a voltage regulator module (VRM) to supply a voltage tocomponents at the CPU die; a body bias generator to adjust body voltagesof transistor devices on the CPU die; and a control circuit to controlthe transistors on the CPU die.
 15. The system of claim 14 wherein thepower management die further comprises: a voltage sensor; and atemperature sensor.
 16. The system of claim 15 further comprising I/Oconnections coupled between the power management die and the CPU die.17. The system of claim 13 wherein the CPU further comprises a packagesubstrate bonded to the power management die.